The immediate objective is comprehensive physiological-biochemical-morphological evaluation of the effects of heavy metal, petroleum and organochlorine pollutants on osmoregulatory and nutritive membrane functions in selected species of aquatic birds and fish. The decision to focus on these particular aspects of membrane toxicity is based, in part, on fragmentary data from Mount Desert and other laboratories already suggesting disruption of osmoregulatory and/or nutritive transport in these species. The long-term objective is to evaluate the role of altered membrane as one of the primary mechanisms by which various pollutants exert toxic effects on living cells. The cell membrane theory of toxicity offers a rational approach to 1) explaining toxicities of known pollutants, 2) designing indicator tests for environmental warning, and 3) predicting future health hazards including synergistic actions. For example, we have successfully explained a classical environmental warning, DDT-induced eggshell thinning, by evaluating toxic effects on calcium transport in avian shell gland epithelium.